A promising development in the field of regenerative medicine has been the isolation and propagation of human stem cells from the early embryo. These cells have two very special properties: First, unlike other normal mammalian cell types, they can be propagated in culture almost indefinitely, providing a virtually unlimited supply. Second, they can be used to generate a variety of tissue types of interest as a source of replacement cells and tissues for use in therapy.
Thomson et al. (Science 282:114, 1998; U.S. Pat. No. 6,200,806) were the first to successfully isolate and propagate embryonic stem cells from human blastocysts. Gearhart and coworkers derived human embryonic germ cell lines from fetal gonadal tissue (Shambloft et al., Proc. Natl. Acad. Sci. USA 95:13726, 1998; U.S. Pat. No. 6,090,622).
International Patent Publication WO 99/20741 (Geron Corp.) describes methods and materials for the growth of primate-derived primordial stem cells. International Patent Publication WO 01/51616 (Geron Corp.) provides techniques for growth and differentiation of human pluripotent stem cells. An article by Xu et al. (Nature Biotechnology 19:971, 2001) describes feeder-free growth of undifferentiated human embryonic stem cells. Lebkowski et al. (Cancer J. 7 Suppl. 2:S83, 2001) discuss the culture, differentiation, and genetic modification of human embryonic stem cell for regenerative medicine applications. These publications report exemplary culture methods for propagating human embryonic stem cells in an undifferentiated state, and their use in preparing cells for human therapy.
Markers for identifying undifferentiated pluripotent stem cells include SSEA-4, Tra-1-60, and Tra-1-81 (Thomson et al. and Gearhart et al., supra). They also express human telomerase reverse transcriptase, and the POU transcription factor Oct 3/4(WO 01/51616; Amit et al., Dev. Biol. 227:271, 2000; Xu et al., supra).
Loring et al. (Restor. Neurol. Neurosci. 18:81, 2001) review gene expression profiles of embryonic stem cells and ES-derived neurons. Pesce et al. (Bioessays 20:722, 1998) comment on the potential role of transcription factor Oct-4 in the totipotent germ-line cycle of mice. Gajovic et al. (Exp. Cell Res. 242:138, 1998) report that genes expressed after retinoic acid-mediated differentiation of embryoid bodies are likely to be expressed during embryo development. Zur Nieden et al. (Toxicol. in Vitro 15:455, 2001) propose certain molecular markers for embryonic stem cells. Henderson et al. (Stem Cells 20:329, 2002) report that pre-implantation human embryos and ES cells have comparable expression of SSEAs. Tanaka et al. (Genome Res. 12:1921, 2002) profile gene expression in mouse ES cells to identify candidate genes associated with pluripotency and lineage specificity. Draper et al. (J. Anat. 299:249, 2002) review change of surface antigens of human embryonic stem cells upon differentiation in culture.
Kelly et al. (Mol Reprod. Dev. 56:113, 2000) report DNA microarray analyses of genes regulated during the differentiation of embryonic stem cells. Woltjen et al. (Nucl. Acids Res. 28:E41, 2000) report retro-recombination screening of a mouse embryonic stem cell genomic library. Monk et al. (Oncogene 20:8085, 2001) list human embryonic genes re-expressed in cancer cells. Tanaka et al. (Genome Res. 12:1921, 2002) discuss gene expression profiling of embryo-derived stem cells, and candidate genes putatively associated with pluripotency and lineage specificity. Monk et al. report developmental genes identified by differential display (Reprod. Fertil. Dev. 13:51, 2001). Natale et al. (Reprod. 122:687, 2001) characterize bovine blastocyst gene expression patterns by differential display RT-PCR.
Fan et al. (Dev. Biol. 210:481, 1999) propose that forced expression of the homeobox-containing gene Pem blocks differentiation of embryonic stem cells. Abdel-Rahman et al. (Hum. Reprod. 10:2787, 1995) report the effect of expressing transcription regulating genes in human preimplantation embryos. Jackson et al. (J. Biol. Chem. 277:38683, 2002) describe the cloning and characterization of Ehox, a homeobox gene that reportedly plays a role in ES cell differentiation.
The following disclosure provides new markers and marker combinations that are effective means to identify, characterize, qualify, and control differentiation of pluripotent cells.